Thursday, 24 February 2011

Solar Flares - Vulnerability of GPS

Whilst GPS is commonly associated with satellite navigation and wayfinding, many technologies and computer networks rely on the GPS satellite system for a source of accurate time.
GPS time servers utilise the onboard atomic clocks of the global positing satellites and use this stable and accurate time source as a basis for their NTP synchronisation (Network Time Protocol)
GPS has become the preferred source of atomic clock time for many network operators. There are other methods where UTC (Coordinated Universal Time) can be used; radio signals and across the internet to name but two sources, but none is as secure or readily available as GPS.
Unlike radio signals, GPS is available everywhere on the planet, is never down for scheduled maintenance and is not commonly vulnerable to interference. It also doesn't have any security implications like connecting across an internet firewall to an online time server can.
However, this doesn't mean GPS is completely invulnerable as recent news reports have suggested.
It has been recently reported that a sunspot (sunspot 1092) the size of the Earth has flared up and a massive coronal ejection (solar flare), described in the press as a "solar tsunami" which was suggested to be large enough to satellites and wreck power and communications grids.
Solar activity, such as sunspots and solar flares (ejected hot plumes of plasma and radiation from the sun), have long been known to be able to damage and even disable satellites.
GPS is particularly vulnerable because of the high orbits of geostationary satellites (some 22,000 miles up) this leaves them unprotected by the earth's magnetic field.
However, following the recent solar activity there has been no reported damage to the GPS system but as so many people rely on satellite navigation and GPS time for NTP servers could a future solar storm lead to havoc on Earth?
Well the short answer is yes; GPS satellites have been in orbit for several decades and while redundant satellites were introduced into the system many have been used up due to previous failures and it would only take a couple of disabled satellite to cause real problems for the network.
Fortunately, help is at hand as the Europeans, Russians and Chinese are all working on their own GPS equivalents which should work hand-in-hand with the American GPS network allowing GPS receivers to pick and choose from all four GNSS networks (Global Navigational Satellite Systems) ensuring that even if a really violent solar storm hits in the future there will be more than enough geo stationary satellites to ensure no loss of signal.
Richard Hawkesford and Richard Williams are technical authors and specialists in atomic clocks, telecommunications, NTP and network time synchronisation helping to develop dedicated NTP clocks. Please visit us for more information about an NTP server or other NTP time server solutions.